The present invention relates generally to a method and system to improve efficiency and performance of a power supply and more particularly to a method and system to provide a consistent voltage level into a multiple-pole circuit breaker.
Circuit breakers to protect residential environments are generally known in the art and are mandated by electrical codes. Ground fault protection to residential circuit breakers is also known in the art, as well as arcing fault circuit interrupters. Arcing fault circuit interrupters are utilized in power distribution systems to “trip” a circuit in the presence of an arc fault-type current flow. For example, an arc fault condition exists when an electrical arc forms between the current-carrying phases and neutral phase above a designated threshold specified in electrical codes.
Circuit breakers having ground fault and arc fault circuit interrupting functions rely on electronic trip units, and an internal power supply is typically used to provide power thereto.
The electrical codes provide a limit for a maximum time interval after power-up of fault circuit interrupters, for which the trip unit must actuate in response to a fault condition. This time interval, including power supply charging time, is typically no more than 25 milliseconds. Charging the power supply typically consumes a large percentage of this time interval, which requires the power turn-on time to be fairly rapid. But rapid charging of the power supply, combined with high resistance levels in the circuit, can generate a significant amount of unwanted heat in the circuit. Thus, it is desirable for the internal power supply to power up the electronic trip unit as rapidly as possible, while at the same time reduce the steady state heat generation within the power supply that results after the rapid power-up.
A trip unit power supply within a circuit breaker can typically derive power either directly from the power line for which the circuit breaker is configured to protect, or indirectly from current transformers around the power line. It is advantageous to maintain consistent power to the trip unit, irrespective of current flow through the power line. Since transformers generate electrical potential only during current flow, they are ineffective in providing the consistent power to the trip unit power supply that is desired. Hence, trip unit power supplies for circuit breakers are typically powered directly from the power line voltage.
Existing power supplies for circuit breakers do not address the need described above related to fast power up capability while at the same time avoiding generation of excessive heat within the circuit. In addition, because of the advantages of having a consistently powered circuit breaker, they should not be powered from current transformers for the previously mentioned reasons. It would therefore be beneficial to power the circuit breakers directly from the power line for which they are protecting. Thus, there is a need to have a power supply that powers the trip unit of a circuit breaker consistently, reduces the amount of heat generated within the circuit, and increases speed and consistency of circuit “turn-on” (or power-up) times.